.\"
.\" This file is part of RGBDS.
.\"
.\" Copyright (c) 2010-2019, Anthony J. Bentley and RGBDS contributors.
.\"
.\" SPDX-License-Identifier: MIT
.\"
.Dd July 8, 2019
.Dt RGBASM 1
.Os
.Sh NAME
.Nm rgbasm
.Nd Game Boy assembler
.Sh SYNOPSIS
.Nm
.Op Fl EhLVvw
.Op Fl b Ar chars
.Op Fl D Ar name Ns Op = Ns Ar value
.Op Fl g Ar chars
.Op Fl i Ar path
.Op Fl M Ar depend_file
.Op Fl o Ar out_file
.Op Fl p Ar pad_value
.Op Fl r Ar recursion_depth
.Op Fl W Ar warning
.Ar
.Sh DESCRIPTION
The
.Nm
program creates an RGB object file from an assembly source file.
The input
.Ar file
can be a file path, or
.Cm \-
denoting
.Cm stdin .
.Pp
Note that options can be abbreviated as long as the abbreviation is unambiguous:
.Fl Fl verb
is
.Fl Fl verbose ,
but
.Fl Fl ver
is invalid because it could also be
.Fl Fl version .
The arguments are as follows:
.Bl -tag -width Ds
.It Fl b Ar chars , Fl Fl binary-digits Ar chars
Change the two characters used for binary constants.
The defaults are 01.
.It Fl D Ar name Ns Oo = Ns Ar value Oc , Fl Fl define Ar name Ns Oo = Ns Ar value Oc
Add a string symbol to the compiled source code.
This is equivalent to
.Ql Ar name Ic EQUS \(dq Ns Ar value Ns \(dq
in code, or
.Ql Ar name Ic EQUS \(dq1\(dq
if
.Ar value
is not specified.
.It Fl E , Fl Fl export-all
Export all labels, including unreferenced and local labels.
.It Fl g Ar chars , Fl Fl gfx-chars Ar chars
Change the four characters used for gfx constants.
The defaults are 0123.
.It Fl h , Fl Fl halt-without-nop
By default,
.Nm
inserts a
.Ic nop
instruction immediately after any
.Ic halt
instruction.
The
.Fl h
option disables this behavior.
.It Fl i Ar path , Fl Fl include Ar path
Add an include path.
.It Fl L , Fl Fl preserve-ld
Disable the optimization that turns loads of the form
.Ic LD [$FF00+n8],A
into the opcode
.Ic LDH [$FF00+n8],A
in order to have full control of the result in the final ROM.
.It Fl M Ar depend_file , Fl Fl dependfile Ar depend_file
Print
.Xr make 1
dependencies to
.Ar depend_file .
.It Fl o Ar out_file , Fl Fl output Ar out_file
Write an object file to the given filename.
.It Fl p Ar pad_value , Fl Fl pad-value Ar pad_value
When padding an image, pad with this value.
The default is 0x00.
.It Fl r Ar recursion_depth , Fl Fl recursion-depth Ar recursion_depth
Specifies the recursion depth at which RGBASM will assume being in an infinite loop.
.It Fl V , Fl Fl version
Print the version of the program and exit.
.It Fl v , Fl Fl verbose
Be verbose.
.It Fl W Ar warning , Fl Fl warning Ar warning
Set warning flag
.Ar warning .
A warning message will be printed if
.Ar warning
is an unknown warning flag.
See the
.Sx DIAGNOSTICS
section for a list of warnings.
.It Fl w
Disable all warning output, even when turned into errors.
.El
.Sh DIAGNOSTICS
Warnings are diagnostic messages that indicate possibly erroneous behavior that does not necessarily compromise the assembling process.
The following options alter the way warnings are processed.
.Bl -tag -width Ds
.It Fl Werror
Make all warnings into errors.
.It Fl Werror=
Make the specified warning into an error.
A warning's name is appended
.Pq example: Fl Werror=obsolete ,
and this warning is implicitly enabled and turned into an error.
This is an error if used with a meta warning, such as
.Fl Werror=all .
.El
.Pp
The following warnings are
.Dq meta
warnings, that enable a collection of other warnings.
If a specific warning is toggled via a meta flag and a specific one, the more specific one takes priority.
The position on the command-line acts as a tie breaker, the last one taking effect.
.Bl -tag -width Ds
.It Fl Wall
This enables warnings that are likely to indicate an error or undesired behavior, and that can easily be fixed.
.It Fl Wextra
This enables extra warnings that are less likely to pose a problem, but that may still be wanted.
.It Fl Weverything
Enables literally every warning.
.El
.Pp
The following warnings are actual warning flags; with each description, the corresponding warning flag is included.
Note that each of these flag also has a negation (for example,
.Fl Wempty-entry
enables the warning that
.Fl Wno-empty-entry
disables).
Only the non-default flag is listed here.
Ignoring the
.Dq no-
prefix, entries are listed alphabetically.
.Bl -tag -width Ds
.It Fl Wno-assert
Warns when
.Ic WARN Ns No -type
assertions fail. (See
.Dq Aborting the assembly process
in
.Xr rgbasm 5
for
.Ic ASSERT ) .
.It Fl Wbuiltin-args
Warn about incorrect arguments to built-in functions, such as
.Fn STRSUB
with indexes outside of the string's bounds.
This warning is enabled by
.Fl Wall .
.It Fl Wdiv
Warn when dividing the smallest negative integer by -1, which yields itself due to integer overflow.
.It Fl Wempty-entry
Warn when an empty entry is encountered in a
.Ic db , dw , dl
list.
This warning is enabled by
.Fl Wextra .
.It Fl Wlarge-constant
Warn when a constant too large to fit in a signed 32-bit integer is encountered.
This warning is enabled by
.Fl Wall .
.It Fl Wlong-string
Warn when a string too long to fit in internal buffers is encountered.
This warning is enabled by
.Fl Wall .
.It Fl Wobsolete
Warn when obsolete constructs such as the
.Ic jp [hl]
instruction or
.Ic HOME
section type are encountered.
This warning is enabled by
.Fl Wextra .
.It Fl Wshift
Warn when shifting right a negative value.
Use a division by 2^N instead.
.It Fl Wshift-amount
Warn when a shift's operand is negative or greater than 32.
.It Fl Wno-truncation
Warn when an implicit truncation (for example,
.Ic db )
loses some bits.
.It Fl Wno-user
Warn when the
.Ic WARN
built-in is executed. (See
.Dq Aborting the assembly process
in
.Xr rgbasm 5
for
.Ic WARN ) .
.El
.Sh EXAMPLES
You can assemble a source file in two ways.
.Pp
Straightforward way:
.Dl $ rgbasm -o bar.o foo.asm
.Pp
Pipes way:
.Dl $ cat foo.asm | rgbasm -o bar.o -
.Dl $ rgbasm -o bar.o - < foo.asm
.Pp
The resulting object file is not yet a usable ROM image\(emit must first be run through
.Xr rgblink 1
and then
.Xr rgbfix 1 .
.Sh BUGS
Please report bugs on
.Lk https://github.com/rednex/rgbds/issues GitHub .
.Sh SEE ALSO
.Xr rgbasm 5 ,
.Xr rgbfix 1 ,
.Xr rgblink 1 ,
.Xr rgbds 5 ,
.Xr rgbds 7 ,
.Xr gbz80 7
.Sh HISTORY
.Nm
was originally written by Carsten S\(/orensen as part of the ASMotor package, and was later packaged in RGBDS by Justin Lloyd.
It is now maintained by a number of contributors at
.Lk https://github.com/rednex/rgbds .
